The invention pertains to a catalytic process for coupling allylic compounds and substituted olefins. In another aspect this invention relates to a catalytic process for intra-molecular, carbon-carbon coupling of allylic and substituted olefinic groups which are present in the same compound. Yet in another aspect this invention relates to a catalyst system for coupling allylic and substituted olefinic groups wherein the catalyst system is comprised of a Group VIII metal component, a bromine or iodine component, and a Group V A component. In still another aspect this invention relates to a catalytic process for preparing sorbates and related compounds.
The present method for producing sorbic acid and related compounds involves the reaction of ketene and crotynaldehyde which results in an intractable polymer which must be acid hydrolyzed. The hydrolysis of the polymer results in a mixture of products requiring repeated and difficult separation and purification procedures.
The preparation of sorbates and related compounds because of their multiple functionality, can also involve numerous and cumbersome process steps employing exotic starting materials. For example, the art has recently reported that allyl bromide, tributyl amine can be reacted with methyl acrylate to form methyl sorbate and tributyl ammonium bromide in the presence of palladium acetate and triphenyl phosphine however the use of a stoichiometric amount of the bromide reduces the attractiveness of the process. The elimination of the requirement of stoichiometric bromide in sorbate production would represent an important advancement over the art.
Prior to the catalytic process of this invention, coupling of allylic compounds and substitued olefins required the inventive catalytic process, the art is presented with a more feasible route to doubly unsaturated, substituted hydrocarbons using available and inexpensive starting materials. For example, a route to sorbic acid and its derivatives from allyl alcohol and methyl acrylate is provided by the use of the catalyst system comprising a Group VIII component, a halogen component, and a Group V A component. The inventive reaction of allylic compounds with substituted olefinic compounds allows both the metal components of the catalyst system and the halogen components to be present in substantially less than stoichiometric amounts.